1. Field of the Invention
The present invention relates to an improved process for activating peroxide-based bleaches. In addition, it relates to bleach and bleach-containing detergent compositions which alone or in combination with other ingredients, can be added to an aqueous medium to effect the bleaching of fibrous materials and other bleachable substances over a wide range of temperatures.
2. Description of the Prior Art
Peroxide-based bleaches, such as hydrogen peroxide and perborates, are well known in the art and have been used for a number of years for bleaching textiles, and more recently, in home laundering applications for the bleaching of fabrics which cannot be safely bleached with chlorine-based bleaches because of problems with fiber and/or color damage. However, for home laundering use peroxide-based bleaching agents generally have the disadvantage, as compared to chlorine-based bleaches, that their bleaching effectiveness falls off rapidly as the temperature decreases. For example, peroxide-based bleaches are relatively ineffective at 60.degree.-160.degree. F., which are typical temperatures for home laundering in the United States.
Considerable effort has been devoted over the years to improve the effectiveness of peroxide-based bleaches at lower temperatures. As a result of this effort a variety of compounds have been discovered which activate peroxide-based bleaches. Representative of such activators are the carboxylic acid amide activators disclosed in Dithmar et al U.S. Pat. No. 2,898,181, the organic nitrile activators disclosed in a later Dithmar et al patent, U.S. Pat. No. 2,927,840, the imide activators disclosed in Murray U.S. Pat. No. 3,928,223, the halotriazine activators disclosed in Villaume U.S. Pat. No. 3,945,937 and Loffelman et al U.S. Pat. No. 3,947,374 and U.S. Pat. No. 3,986,971, and the acyl nitrile activators disclosed in Loffelman et al U.S. Pat. No. 3,986,972. Among the more recently discovered and highly effective peroxide-based bleach activators are acid cyanamide and certain metal cyanamides described in Kravetz et al U.S. Pat. No. 4,025,453, Kravetz et al U.S. Pat. No. 4,086,175 and Kubitschek et al U.S. Pat. No. 4,086,177.
Despite the extensive efforts devoted by those skilled in the art to finding suitable activators for peroxide-based bleaches, there is in the United States today little practical application of this technology, although some of the more recently discovered activators do show commercial promise. However, there remains a continuing need in the art for even more effective activators, which are also storage stable, non-toxic and do not have an unpleasant odor. The present invention provides a bleach activation process and related compositions based on a novel class of activators, which when employed under alkaline conditions provide substantially improved bleaching activity, and do not suffer from the drawbacks found with most of the prior art activators, or at least to a substantially lesser degree.